1. Field of the Invention
The present invention relates to a non-sliding vacuum gate valve, and, more particularly, to a novelly improved non-sliding vacuum gate valve which allows the occurrence of particles to be minimized.
2. Description of the Related Art
An example of a construction of a conventional non-sliding vacuum gate valve is disclosed by the present applicant in U.S. Pat. No. 5,002,255.
In the construction of this valve example, a valve rod is moved downward and a valve body is positioned on valve seats at the openings of a valve housing. Then this valve rod is tilted to push the valve body against the valve seats, thereby closing the opening of the valve box.
Conventional non-sliding vacuum gate valves, which have the above-described construction, have the following problems.
The valve is closed when the valve rod is longest. This results in larger valves because a large-diameter valve rod is used to maintain the strength thereof.
In addition, since the valve rod and the valve body are connected by springs in a freely operable manner, it is impossible to prevent particles from being produced during operation. This makes them unsuitable for use in a chamber of a semiconductor producing device, employed in a clean room which must be kept very clean.
Further, when the valve rod is tilted by air cylinders and arm members, it is impossible to prevent particles from being produced from the portion where pushing members and the arm members contact one another.
Still further, since it is extremely difficult to open the valve box in a sealed state after assembly, it is troublesome, for example, to exchange the O-rings of the valve body.
In the conventional construction, opening and closing operation speed are reduced because linear movement and tilting are performed in connection with each other.